Drop hammer



July 14, 1931. 5. sMlTH 1,814,193

DROP HAMMER Filed March 13, 1925 2 Sheets' Sheet 1 NVENTOR Gran) 2'. 5ml7/l- BY W ATT RNEYS July-14,1931. jismm 1,814,193

DROP HAMMER Filed March 15, 1925 2 Sheets-Sheet 2 INVENTOR 234107 ATZRNEYSZ Patented July 14, 1931 UNITED STATES PATENT OFFICE GRANT E. SMITH, OF POUGHKEEPSIE, NEW YORK, ASSIGNOR TO POUVAILSMITH COR- PORATION, OF POUGHKEEPSIE, NEW YORK, A CORPORATION OF NEW YORK DROP HAMMER Application filed March 13, 1925. Serial No. 15,398.

The present invention relates to drop hammers of the type commonly known as board drop hammers and has for an object to provide an improved machine of this character.

The mechanism for raising the head or ram of such drop hammers usually comprises a socalled board secured to the head and opposed rolls arranged to grip the board and by rotation thereagainst to raise it and the ram. The rolls conveniently may rotate constantly in a direction to feed the board in an upward direction therebetween and these constantly rotating rolls may be moved relatively toward each other to grip the board when the ram is to be raised and separated to permit the ram to drop.

Whatever the particular mode of operation of the rolls the effect upon the boards is very destructive. The repeated blows of the hammer which jar the boardsand force the board-securing wedges more tightly into the ram head also have a Very destructive effect upon the secured lower ends of the boards, frequently causing splits at the lower ends which splits, once started, soon extend upwardly and destroy the board. Because of the destructive effects of the rolls and jarring of the ram in use, it has been impossible heretofore to make boards which would be satisfactorily durable and efficient in use especially for hammers of the larger sizes. Boards made of metal have not proved satisfactory in use and boards of wood have not been satisfactorily durable. It has been found, for example, that boards of even the hardest woods will not operate satisfactorily in use for an average of more than two or three days on drop hammers of the larger sizes, such, for example, as one in which the ram weighs two thousand pounds or more. There are several reasons for this: The density and hardness of the wood is not uniform and under the compressive action of the rolls the surface becomes compressed in spots and therefore irregular causing an irregular lifting action; the rolls tend to slip, especially if the boards are irregular and when they slip they char or burn the wood, sometimes to such an extent that the board blazes up and must be quenched; the several parts of the board, because of unfavorable variations in hardness across the width thereof wear unevenly so that the rolls are effectively engaging the board throughout only a portion: of the width thereof; the boards split or crush and work loose where they are wedged into the ram due to the effects of the securing wedges and'the jar in use.

The failure of the board is a serious matter, not only because of the cost of the boards, but also because of the great loss of use of the machine and the cost of labor necessary to replace the used boards. For example, it requires usually the services of two skilled men for an hour to remove a board that has failed and to introduce a new one and secure it rigidly in place, and in the meantime use of the machine is lost.

The present invention provides a more effectively operating drop hammer by providing an improved board which is hard and dense and durable in use and which is provided with a surface with which the lifting rolls co-operate effectively. The nature and objects of the invention will be better understood from a description of a particular illustrative embodiment thereof, for the purposes of which description reference should be had to the accompanying drawings forming a part hereof and in which Figure l is a perspective view of a drop hammer embodying the invention;

Figure 2 is a detailed view in front elevation of a board of the drop hammer;

Figure 3 is a view in side elevation of the parts from which the blank is to be made showing the manner of assembling the parts thereof;

Figure 4 is a sectional view taken on the line l4 of Figure 2 of the finished board;

Figure 5 is a sectional view of the blank before the same is compressed showing also the molds in which the board is compressed and formed; and

Figure 6 is a sectional view similar to Figure 5 but showing the parts after compress1on.

The drop hammer shown for'the purposes of illustrating the invention has an anvil. 5

and a head or ram 6 movable to and from the anvil on vertical ways 7. The head is raised by means of a board 8 secured at its lower end to the ram 6 and rolls co-operating with the board. Any desired number of rolls may be used. Only two are employed in the illustrated structure. Only the front roll 9 is shown in Figure 1, the other being directly behind it on the opposite side of the board so that the board may be gripped between the rolls when they are moved relatively together, it being sufficient and usually more practicable to move only one of the rolls, the other being rotatable in a fixed bearing.

The board is made of wood, preferably hard wood, such as ash, birch, maple, or hickory, which in the finished board is compressed sufliciently to compact the fibers, at least throughout the portion of the length of the board which is engaged by the rolls, to form a tough wear-resisting surface for engagement by the rolls and at the lower end to provide a strong section for securing to the ram.

The board may be made in one single piece of any suitable wood or it may be built up in various ways of several pieces of the same or different kinds of wood suitably compressed. If it is built up of several pieces, the several pieces are preferably fitted together and assembled before compression.

I prefer to treat the surface of the board with a coating which will improve its condition especially with respect to the wearresisting qualities. If the board is built up of separate pieces of wood the several separate pieces should be coated with adhesive before they are assembled.

A coating of a phenolic condensation product. may be used advantageously. This material may be used not only to coat the exterior of the board, especially that part which is to be engaged by the rolls, but in the case of a built-up board it may be used to coat the several sections and to serve as an adhesive to bind the sections together. This coating upon application of heat and pressure is first softened and then upon cooling is cured to form a bond between sections and to form on the exterior a hard wear-resisting surface. This coating is indicated by light stippling in Figures 2 and 3.

Referring more specifically to the construction shown in the drawings, the board there shown is made up of three substantially similar strips 10, 11, and 12 of a suitable wood together with inlaid pieces 14, 15 which may be of a harder wood such, for example, as hickory. If desired, the inlaid pieces may be arranged to overlie the joints between the main boards so that the several parts lie in staggered relation. The separate strips, if desired, may be secured together by means of dowel pins 16, 17, 18 extending transversely therethrough. The several meeting faces of the sections of the blank are suitably treated before assembly, with a phenolic condensation product or synthetic resin to serve as an adhesive, and the exterior surfaces are preferably treated with the same material in order to improve the hardness and toughness and, generally speaking, the wear-resisting qualities of the board. The coating may be applied as a solution and allowed to dry and, if desired, an additional quantity of the same material in powdered form may be applied to the surfaces of the blank sections while the solution is still in tacky condition. I prefer also to apply to the portions of the board which in use are to be en aged by the lifting rolls a material such as fire clay which will improve the frictional engagement between the rolls and board and make the surface more durable. To this end, I apply the fire clay to the outer surfaces of the sections 14 and 15 while the adhesive is in tacky condition. This coating is indicated in Figure 2 by heavy stippling. C

After the coated blank sections have thoroughly dried the same are assembled and compressed in a mold under heat and pressure sufficient to reduce the board to, for example, three-quarters or two-thirds of its original volume. In the illustrated construction the board is shown as compressed in the direction of its thickness but it will be understood that this is illustrative merely and the compression may be in any direction if desired.

In the method of molding, selected for particular description, the assembled blank is placed in a two part mold 20, 21 and the mold placed in a press between heated pres sure heads 22, 23. Preferably, but not necessarily, the mold is formed to confine the board at the edges to limit the flow of the wood during compression. A mold of this character is illustrated. After the mold is placed in the press the pressure heads 22, 23 are then applied against the mold parts to press the same against the blank with a light pressure. Heat is then applied to the pressure heads and the mold is allowed to absorb heat from the mold for a predetermined time, for example, for five or ten minutes until the blank becomes heated sufliciently to make it moldable and then the extreme pres- 7 will move relatively and adjust themselves to the configuration of other parts of the blank and of the mold.

The heat of the mold softens and makes plastic the coating and then during the compressing operation the coating is forced into the pores of the wood along the surface thereof and simultaneously cured to form a hard, wear-resisting surface. The coating also acts as a lubricant between the mold and the blank.

The pressure employed may range, for example, from five hundred to five thousand pounds per square inch of the blank depending upon the amount of compression desired, the material compressed and other particular features characteristic of the material, finish or mold. The temperature at which the operation is performed may vary considerably. Successful results have been obtained in compressing wood block blanks at temperatures which approximate 800 F. I find it convenient to heat the pressure heads by steam under a pressure of about eightyfive pounds per square inch circulated in suitable passages 24, 25 therein. The molds,

may be cooled when the compressing operation is finished by circulating water in these passages.

The foregoing description is illustrative merely and is not intended as defining the limits of the invention.

hat I claim is:

1. A board drop hammer comprising in combination a movable head, a board secured to said head and projecting therefrom and rolls engageable with said board to raise the movable head, said board being built up of sections separately coated with a phenolic condensation product and assembled in staggered relation and then reshaped under pressure.

2. A board drop hammer comprising in combination a movable head, a board secured to said head and projecting therefrom and rolls engageable with said board to raise the movable head, said board being formed of sections of wood, the sections along the surface of the board at the point of engagement with the rolls being of harder wood than the remaining sections and the whole being compressed under heat and pressure to substantially reduce the volume of the board.

3. A board for a board" drop hammer comprising a number of parallel wood blanks with an inlay of harder wood along one surface thereof, said blank and inlay being molded together and compressed under heat and pressure to substantially reduce the size thereof.

4. A board drop hammer comprising in combination a movable head, a board secured to said head and projecting therefrom and rolls engageable with said board to raise the movable head, said board being formed of sections separately coated with synthetic resin and assembled in staggered relation and then reshaped under pressure.

5. A board for drop hammers built up of sections separately coated with a phenolic condensation product assembled in staggered relation and then reshaped under pressure.

6. A board for drop hammers comprising sections assembled in staggered relation and reshaped under pressure.

7. A board for drop hammers comprising separate sections assembled in staggered relation and reshaped under heat and pressure.

8. A board for drop hammers comprising a body portion of fibrous material and a surface reinforcement of a different fibrous material, the whole being permanently cleformed.

9. A board for drop hammers comprising a. body portion of fibrous material and a facing of a different fibrous material, the whole being permanently deformed under heat and pressure.

10. A board for drop hammers comprising a body portion of fibrous material and a facing of a different fibrous material, the whole being deformed under heat and pressure and at the same time given a treatment with a curing compound to maintain it in deformed condition.

In testimony whereof, I have signed my name to this specification this 7th day of March, 1925.

GRANT E. SMITH. 

